[with patch, positive review] Memory leak in pickling matrices of GF(2)

[rlm]

This is in sage-3.1.2.rc1.

If I do

sage: L = [random_matrix(GF(2), 20, 20) for _ in xrange(10^5)]

then my process is here:

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND          
15889 rlmill    25   0  446m 131m  17m S    0  0.2   0:06.30 sage-ipython

Then I do the following:

sage: save(L, 'crap')
sage: del L

And my process is here:

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND          
15889 rlmill    16   0 1471m 1.1g  17m S    0  1.8   1:02.37 sage-ipython

[mabshoff]

Oops, with 10^4 elements:

==27766== LEAK SUMMARY:
==27766==    definitely lost: 73,004,158 bytes in 10,007 blocks.
==27766==    indirectly lost: 5,586,420 bytes in 209,482 blocks.
==27766==      possibly lost: 402,505 bytes in 1,011 blocks.
==27766==    still reachable: 36,106,357 bytes in 217,055 blocks.
==27766==         suppressed: 305,691 bytes in 4,843 blocks.

Cheers,

Michael

[mabshoff]

Before:

==27766== LEAK SUMMARY:
==27766==    definitely lost: 73,004,158 bytes in 10,007 blocks.
==27766==    indirectly lost: 5,586,420 bytes in 209,482 blocks.
==27766==      possibly lost: 402,505 bytes in 1,011 blocks.
==27766==    still reachable: 36,106,357 bytes in 217,055 blocks.
==27766==         suppressed: 305,691 bytes in 4,843 blocks.

Specifically:

==27766== 78,589,900 (73,003,480 direct, 5,586,420 indirect) bytes in 9,995 blocks are definitely lost in loss record 13,758 of 13,758
==27766==    at 0x4A1BDEB: malloc (vg_replace_malloc.c:207)
==27766==    by 0x16A44C5E: gdMalloc (gdhelpers.c:85)
==27766==    by 0x16A2E130: gdImageCreate (gd.c:83)
==27766==    by 0x166C828B: __pyx_pf_4sage_6matrix_17matrix_mod2_dense_17Matrix_mod2_dense___reduce__ (matrix_mod2_dense.c:6925)
==27766==    by 0x415832: PyObject_Call (abstract.c:1861)
==27766==    by 0x47D750: PyEval_CallObjectWithKeywords (ceval.c:3442)
==27766==    by 0x458C0F: object_reduce_ex (typeobject.c:2867)
==27766==    by 0x415832: PyObject_Call (abstract.c:1861)
==27766==    by 0x7D86723: save (cPickle.c:2498)
==27766==    by 0x7D87ECC: batch_list (cPickle.c:1561)
==27766==    by 0x7D86C5B: save (cPickle.c:1629)
==27766==    by 0x7D88587: cpm_dumps (cPickle.c:2580)

After:

==29605== LEAK SUMMARY:
==29605==    definitely lost: 678 bytes in 12 blocks.
==29605==      possibly lost: 369,938 bytes in 975 blocks.
==29605==    still reachable: 36,091,754 bytes in 216,569 blocks.
==29605==         suppressed: 305,691 bytes in 4,843 blocks.

[mabshoff]

Merged in Sage 3.1.2.rc3